1. Field
Disclosed herein is a synergistic herbicidal composition, particularly a synergistic herbicidal composition that can be applied in fields of resistant rapes, resistant soybeans and other crops.
2. Description of Related Art
Clethodim is also called Selectione or Seroxat. The chemical name thereof is: (±)-2-[(E)-3-chloroallyloxyimino]propyl-5-[2-(ethylthio)propyl]-3-hydroxycyclohexen-2-one, and the structure formula thereof is:

Clethodim is a postemergence cyclohexenone herbicide for dry field with excellent selectivity. It is suitable for broadleaf fields such as soybean, rape, cotton, peanut, etc., to control Gramineae weeds, such as wild oat, Digitaria, Setaria, goosegrass, Poa, hard grass, etc. After application, it can be rapidly absorbed and transmitted to the shoot tip and meristem by the stems and leaves of Gramineae weeds, and inhibits the activity of the meristem, disrupts cell division, and eventually leads to the death of the weeds.
The chemical name of sethoxydim is (±)-2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclo hexen-1-one, and the structure formula thereof is:

Sethoxydim, which also belongs to the group of cyclohexenone herbicides, is a highly selective systemic conductive stem leaf processing agent, and can be rapidly absorbed by the stems and leaves of Gramineae weeds, and transmitted to the top and internode meristems, such that Gramineae weeds are killed by disrupting cell divisions. It can be used for crops such as soybean, cotton, rape, peanut, potato, beet, sunflower, flax, etc., and for orchards, to control barnyard grass, wild oat, Setaria, Alopecurus, Digitaria, goosegrass, etc., but it is ineffective with respect to broadleaf weeds.
The development of sulfonylurea herbicides began in the late 1970's. It has been reported by Levitt et al. in 1978 that preemergence soil treatment or postemergence foliar treatment with chlorsulfuron at a very low dosage can effectively control the majority of weeds in the fields of wheat and flax. This was followed by the development of metsulfuron-methyl, and a series of other sulfonylurea compounds, such as sulfometuron methyl, chlorimuron-ethyl, tribenuron-methyl, thifensulfuron-methyl, bensulfuron-methyl, etc. have been developed subsequently. The development of these herbicides has been very rapid and they have been used in the fields of various crops. Some of the sulfonylurea herbicides have become the main herbicides used in fields of certain crops. Moreover, new compounds of sulfonylurea herbicides continue to be developed and commercialized. Sulfonylurea herbicides generally can be thought of as consisting of three moieties, i.e., an aromatic group, a sulfonylurea bridge, and a heterocyclic ring. Small changes in the substituents of one or more moieties can cause significant changes in biological activity and selectivity. The more common sulfonylurea herbicide products include: thifensulfuron-methyl, having the chemical name of: 3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-1-(2-methoxyformylthiophen-3-yl)-sulfonylurea; tribenuron-methyl, having the chemical name of: methyl 2-[N-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-N-methylcarbamoylaminosulfonyl]benzoate; cyclosulfamuron, having the chemical name of: 1-{[O-(cyclopropylcarbonyl)phenyl]sulfamoyl}-3(4,6-dimethoxy-2-pyridinyl)-urea; bensulfuron-methyl, having the chemical name of: methyl 2-[((4,6-dimethoxypyrimidin-2-yl)aminocarbonylamino]sulfonyl methyl)benzoate; triasulfuron, having the chemical name of: 1-[2-(2-chloroethoxy)phenylsulfonyl]-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)urea; mesulfuron-methyl, having the chemical name of: methyl 2-[(4,6-dimethoxypyrimidin-2-ylcarbamoyl)sulfamoyl]-α-(methanesulfonamido)-p-toluate; monosulfuron, having the chemical name of: 2-(4-methylpyrimidinyl)benzenesulfonylurea; amidosulfuron, having the chemical name of: 1-(4,6-dimethoxypyrimidin-2-yl)-3-mesyl(methyl)sulfamoylurea; metsulfuron-methyl, having the chemical name of: methyl 2-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)ureidosulfonyl]benzoate; chlorsulfuron, having the chemical name of: 1-(2-chlorophenyl)sulfonyl]3-(4-methyl-6-methyl-1,3,5-triazin-2-yl)urea; nicosulfuron, having the chemical name of: 2-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-N,N-dimethylnicotinamide.
Even with the existence of these herbicides, there remains a need in the art to control all the weeds in the field at one time, to expand the limit of herbicidal spectra of clethodim and sethoxydim herbicides and sulfonylurea herbicides, and to improve the herbicidal speed of clethodim or sethoxydim and sulfonylurea herbicides against dicotyledonous and monocotyledonous weeds.